It's not the cost, it's the hassle of everything... I just have a ton of other things to do this weekend...

 

Okay no problem I'll hunt for one down here.
Thanks

 

a few reasons for you symptom . bent valve , spark plug wire on wrong cylinder , timing chain slip same if its a belt . even if the timing is controled by the ECM a belt that has SKIPPED a tooth will show your symptom , how many miles on your car ? if you have over 100,000miles 10:1 bad timing chain - belt also check your distributor cap for cracks or hairline fractures ,bad rotor ? these suggestions are for if you have popping and back fireing while driving otherwise like the other guys have said , bad fuel pump

 

you will also want to do a leak test by charging the cylinders with air to see if you have a bent valve . bad intake valve you will hear the air coming out of the intake ,bad exhust valve you will hear the air coming out of the exhust pipe . hope this helps

 

I have changed the spark plugs and leads as well as the distributor and rotor.
I have already replaced the timing belt and checked the timing several time.

Today I installed another fuel pump and that didn't work as well then I replaced the Fuel pressure regulator and still didn't work.

Any other suggestion would be appreciated.

Thanks
Guys

 

It not uncommon to replace parts with defective ones. That is why diagnostics / tests are so important.

You had a way-too-low fuel pressure before -- what's the fuel pressure with the new pump?

Secondly, did you go through the procedure (pinch the return hose etc.), like gdog advised you to?

I know sometimes it's hard, but try to be patient, and take it small step by small step...

 

Backfiring thru the intake, appears to be a timing issue and you might check the ecu(m) again since you have ruled out the simpler parts. Please pardon my lack of knowledge on this part.. If timing is to insure spark when piston is in proper position, if a cam is off timing (tooth?) could it also cause some of your problem? I think the CPS might have something to do with it but....
245lbs/in compression? Did not see an update to this. If compression is that high then it possible for lower octane fuel/air mixture to pre-ignite(rough running), which can effect valves. Probably would also note some dieseling at turn off. Sorry but that would more likely occur due to higher temp and I believe you said it was normal.

 

I installed another pump and I checked the fuel pressure and it was 42psi same as the other pump.
I tried another used pump with the same pressure and no change.
I also replaced the fuel pressure regulator with no change when I pinched the return line the pressure goes up a lot and the engine revs up as well.

I also checked the compression again and this time I wrote it down.
Cylinder 1-5
(1) 185lbs
(2) 190lbs
(3) 190lbs
(4) 195lbs
(5) 185lbs


A friend told me that he had similar issues with a Catalytic converter problem were the engine has no power when accelerating at certain rpms.
Could this be a possibility and how can I test it?

Thanks

 

Two ways to test the Cat:

1- Take a BFH and hit it. If you hear rocks rattling inside, it's no good.
2- Vacuum Gauge, take speed to 2000 rpm. If Gauge's needle drops to 0, you have too much back-pressure.

BTW: what was your fuel pressure at WOT?